Effect of Condensed Phosphate on the Precipitate Formation and Dispersion of Calcium Phosphate in Water

概要

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Fine particles of calcium phosphate were obtained by mixing K_2HPO_4 and CaCl_2 in 154mM NaCl in the presence of condensed phosphate. The effects of condensed phosphate on the particle formation of amorphous calcium phosphate (ACP), on the transformation of ACP to hydroxyapatite (HAP), and on the dispersibility of ripened HAP particles were studied by means of a Coulter counter, a calcium-ion specific electrode, X-ray powder diffraction analysis, and so on. The effective concentration of the condensed phosphate to retard the transformation of ACP to HAP was found to be between 10^<-4> and 10^<-3>mM ; that to disperse the particles sufficiently was between 10^<-3> and 10^<-2> mM ; and that to disaggregate ripened HAP particles was between 3 and 10^2 mM. The order of effectiveness of the condensed phosphate was common irrespective of the measuring method : hexametaphosphate>triphosphate>diphosphate. Adsorption and/or competitive adsorption of condensed phosphate and orthophosphate, which is the lattice ion of calcium phosphate, was taken into account to explain the above results. The physiological significance of the present work is briefly discussed.
公益社団法人日本薬学会の論文
1985-11-25